I'm lost...
 

Ok, so I have a '04 6spd that I have had for about half a year, and I have had a stuttering issue from day one.

I've tried cleaning the MAF, that did not affect anything. Then a few days ago I got around to removing the SSV and cleaning it and inside the housing. I ran it and it helped the stutter a lot, but it's still there. It used to be very rough at around 7500 rpm, and now it is a very sudden maybe half second pause at around 8000 rpm. I bought a used Cobb AP and installed it with the stage 1 tune, and it completely got rid of the stutter, but only for one drive cycle. What happened was I installed the AP and went for a very long drive. The entire time the stutter was gone. But then the same night I went back out, but the stutter was back. I am no longer going to run the stage 1 tune but and going to get a custom tune done.

But I'm wondering, could the stutter still be there because I did not clean the SSV properly? Was I supposed to dissasemble anything when I cleaned the SSV? Because all I did was spray the valve with carb cleaner and wiped it clean, the did the same for the housing.

Is there possibly anything else that it could be that I have overlooked?

You haven't mentioned any of the basics except the MAF.

What's the age and condition of your ignition?

Have you cleaned and reset the ESS?

Have you confirmed no vacuum leaks?

My could and plugs were replaced about a month ago, and I have not cleaned the ESS, because I am searching for more info about that. And no I cannot confirm no vacuum leaks

Pull a 10 second log at idle with the AP and post it up here. Make sure that RPM, STFT, LTFT, MAF, and AFR are turned on for logging.

Ok. I can't promise it will be today but I will get it as soon as possible

Make sure it's a hot idle, and wait for the fans to cycle off.

Alright. Thanks. I'll get it posted tomorrow

Oh and did you want me to do the log with the stage 1 tune?

no with the stock style tune

It doesn't matter, this isn't tune related. I'm confirming the lack or presence of a vacuum leak. Just use whatever tune is loaded.

Ok cool thanks

Data log
 

Attached the data log as a PDF

Yeah, it's going to be tiny, but you have a slight vacuum leak. If that leak is in the vacuum line to the VIV (SSV opens much lower around 3,750rpm), then it could cause your stutter.

The next step is going to see if you can log that stutter :)

Ok. Well what exactly do I have to do? :scratchhe

Same physical logging proces with the AP, just see if you can replicate the stuttering at high RPM, and if you can do it on demand, then start a log recording and do that to get it to stutter, then stop the log, and post it.

Ok, it always stutters when I rev high so I can do that easily. I will do that as soon as I can

And do you want me to log any other things or the same list?

I'm assuming you are at full throttle when it happens, so throttle % really isn't needed, but you can add it. Otherwise the same items are the critical ones.

Ok I'll get it posted in about an hour or two hopefully

Unless you're looking at a different log than the one that's posted I can't comprehend hiw you came to that assessment. Anything under 5% LTFT unadjusted is irrelevant.

Data log attached...

He is over 5% with a low MAF value at the tail end of the log.

Hmm, you go lean in the 4,000 to 5,000rpm range, and you can see the short term fuel trim dumping in up to 20% more fuel to try to richen you up further. There are also several odd points at which your RPM value drops briefly.

I don't specifically see where the high 7,000-8,000rpm stutter is in here, but you definitely have an issue in the 4,000-5,000 range. Is this the stage 1? or the stock tune?

It was the stage 1 tune. And when driving today I noticed that it was acting just like it did when I first installed the tune. It is a very very brief stutter now. Same thing as it was. But it's weird because it went from that, then back to how it was before the tune, and now it's back to a little bit less stutter. But what should I do now?

Do you have an after market air system?

No its the stock one